It's all well and good saying you think all this stuff is unnecessary, but to say this is high level linguistics just makes people sound ignorant. It really is not, and children in other countries learn all this at a young age as well.
I struggle with the unnecessary label as well - who gets to decide what is necessary learning and what isn't? People mourn the loss of time for creative writing - why is creative writing more important? In my whole adult life I have never done any creative writing, so was doing it at school pointless and unnecessary?
I teach MFL and on the whole students don't mind learning grammar, on the contrary - they love how it all makes sense and fits together.